The sea-level projections made by the glaciological community as part of the IPCC process have often been out of phase with the projections considered by the wider CMIP community. For instance in AR5, the ice2sea and SeaRISE ice sheet projects predominantly worked with AR4 scenarios, while the CMIP5 community used new RCP scenarios. A primary focus of this meeting is therefore to develop a plan that will allow ice sheet and glacier models to be better integrated in the CMIP6 initiative, in order to improve both sea level projections due to changes in the cryosphere and our understanding of the cryosphere in a changing climate. These goals map into the Cryosphere Grand Challenge and the Sea-Level Rise Grand Challenge relevant to CliC and the WCRP. Participation is by invitation only, and will primarily include ice sheet and Earth system model development and analysis leaders, representatives of MIPs that are relevant to the cryosphere and observation data set providers. If you would like to be invited to the meeting or if you would like to join the meeting remotely, the first session will be shared via webex for the images and telecom for the sound, please email Sophie Nowicki.

The meeting goal is to develop an Ice Sheet MIP proposal for participation in the CMIP6 initiative.

Meeting Objectives

Assess the utility of the current CMIP5 variables over ice sheets, including formatting, documentation, temporal and spatial resolution. Identify which variables are lacking in the current CMIP5 for our purpose and provide recommendation to CMIP6 for additional variables.

Identify which experiment in the proposed CMIP6 DECK experiment should become the primary focus of the MIP for fully coupled ice sheet - climate models (and how to include feedback for ice models that would be forced “offline”).

Identify whether additional experiments should be proposed in CMIP6.

Identify preliminary sensitivity experiments that focus on understanding the source of diversity in modeled responses and feedbacks, towards reducing the uncertainty in sea-level projections. (For examples, how do different beds of initialization methods affect the projections).

Report back from D + discussion of where we are + identify the experiments.

H114, B33

15.00-15.30

Tea

15.30-17.30

Breakout E: ‘More focussed experiment design + Links to CMIP’

A128,A109, A209 etc

Friday 18th July

Time

Event

Location

8.30-10.30

Report back from E. & Write up of MIP

H114, B33

10.30-11.00

Coffee

11.00-13.00

Governance + Continue Write up + Wrap up

H114, B33

Meeting ends

Breakout sessions will run in parallel and consist of small groups ~6-10 participants. They will normally be split between Greenland, Antarctica and global glaciers, although for some topics other groupings may be necessary. Each breakout will be introduced in plenary by a couple of 10-15 minute talks to give background, highlight key issues and set objectives. Plenary report back sessions will contain a brief summary from each breakout group’s rapporteur followed by synthesis. We will also have additional rooms available, but our main home is H114 in Building 33

How close are we to having models that could run as part of a CMIP-style ESM? And how suitable are CMIP models over the cryosphere?

How many AOGCMs with coupled ice sheet could take part in a MIP? What intermediate configurations would work and how would feedbacks be included? (i.e.: driving ice sheet models “offline”)

How would the ice sheet model be initialized?

Is there scope for a separate AOGCM/RCM inter-comparison for SMB? or ocean circulation around the ice sheets?

Should we have separate global glacier, Greenland and Antarctic efforts?

Greenland - What do we do about fjords? etc

Antarctica - Is the simulation of the Southern Ocean good enough to provide adequate forcing? etc

What other AOGCM forcing will be required and how crucial is its quality, spatial and temporal resolutions? (i.e.: are there any variable lacking in the current CMIP5 output set for our purpose? Are they of the right spatial, temporal resolutions? Should AOGCMs fields be downscaled and how? (see: data described in Amon, Lmon, OImon and LImon at http://cmip-pcmdi.llnl.gov/cmip5/data_description.html)

What are the major obstacles to credible projections of the cryospheric components of sea level?

What physics are missing from models that could be used for projections?

Are there numerical issues that also need to be resolved in both ice-flow and climate models?

Is there a role for parameterizations in bridging some of these gaps? How could these parameterizations be tested?

Is there a need for preliminary inter-comparisons to test suitability of models for inclusion in full MIP?

Greenland. Will we have a credible model of iceberg calving and marine melt of tidewater glaciers? How to cope with uncertainties in bedrock topography, ice rheology, basal slipperiness? Etc

Antarctica. How to cope with uncertainties in bedrock topography, ice rheology, basal slipperiness, marine melt etc all of which may be important for grounding line retreat? Etc

C. MIP experimental design

What type of experiments could we tackle?

Which experiment(s) out of the proposed 5 CMIP DECK experiments should become the focus of our effort? (i.e.: if running only one experiment with a fully-coupled system and repeating with ice sheets driven offline)

Should we suggest an additional experiment to CMIP6?

What are the synergies with other MIPs?

What time scales are of most interest for future work?

What periods would be of interest for simulations of past climate (pre-industrial, Eemian?)

How can we augment on the suite of CMIP DECK experiments?

How can we explore parameter uncertainty?

Are there sensitivity experiments that can investigate the origin and consequence of systematic model bias? Should we have experiments that focus on understanding the source of diversity in modeled responses and feedbacks, towards reducing the uncertainty in sea-level projections? (For example: how do different beds and initialization methods affect the projections)

How can we maximize the combination of whole ice sheet models & flowband models?

What other approaches could be used for projecting changes in the cryosphere and sea-level?

D. Data sets

What data set are needed (model+observations)?

What observational data should we use to initialize the models and for the experiments? (velocities, bedrock topography, geothermal heat-flux etc)

What data should we use to test and validate the models? Both in terms of glaciological observations and climate forcing.

Could we use reanalysis for driving “offline” simulations?

How do we standardize the test data sets?

What fields need to be saved from ice sheet models?

E. Links to CMIP & Write up of MIP

What type of experiments are we tackling, and how will this happen?

Name for the project

Governance

Overview of proposed experiments design & evaluation & analysis.

Science question –or gap- being addressed with these experiments.

What climate variables would be predicted and what would be required from CMIP AOGCMs?

Local information

Where to stay and how to get there:

The closest hotel is the Holiday Inn Greenbelt (7200 Hanover Drive, Greenbelt MD 20770) http://www.ihg.com/holidayinn/hotels/us/en/greenbelt/wasgb/hoteldetailCost varies from $90-135 USD per night. The hotel does not provide transportation from any of the three Washington DC area airports (Baltimore-Washington International, Reagan National and Dulles International). There are various cheaper/slower and expensive/faster options from each.

The Holiday Inn Greenbelt is about 5 min drive from NASA GSFC. The hotel can offer a free shuttle bus upon request to the main gate of GSFC, or participants will be able to share rides in rental cars/taxis.

No meals provided

No lunch will be provided during the meeting but there are cafeterias on the campus, and participants are welcome to bring their own food and eat at any of the picnic tables. There are several restaurants and other food options nearby on Greenbelt Road.